考虑支撑架设时机的基坑围护结构计算方法

摘要

研究目的：本文针对弹性地基梁全量法计算基坑围护结构内力和位移时，内支撑是预加的、计算条件与施工实际不符的不足，提出一种考虑支撑架设时机的围护结构位移和内力计算方法，以提高计算的准确性。　　研究结论：（1）采用弹性地基梁杆系有限元全量法计算围护结构内力和位移时，将内支撑定义为具有初始间隙的仅受压的杆单元，并将支撑架设时围护桩（或围护墙）在该道支撑处已发生的水平位移设置为初始间隙宽度，就可较好地模拟支撑架立时机，使围护结构内力和位移的计算结果更加符合工程实际；（2）弹性地基梁全量法计算基坑围护结构内力和位移时，不考虑支撑架设时机会使围护桩（或围护墙）的侧向位移和弯矩计算值偏小，这是不安全的；（3）本文的研究成果对基坑围护结构的设计和施工有指导意义。%Research purposes:As using the complete analysis method for beam on elastic foundation calculate the internal force as well as the displacement of the deep foundation ditch enclosure structure,the internal bracings was applied in advanced and the calculation condition was inconsistent with the actual of the construction,a method that considered the erection time of the inner bracings was proposed in this paper in order to improve the calculation accuracy. Research conclusions:(1 )As the bar -system FEM complete analysis method for beam on elastic foundation was adopted to calculate the internal force and the displacement of the foundation ditch enclosure structure,the inner bracing was defined as compression -only bar unit with initial gap,and the width of the initial gap was equal to the lateral displacement of fender piles (or enclosure wall)on the point which the inner bracings were applied at the erection time.With that the erection time of the bracings were considered in the model,which makes the internal force and displacement calculations of the enclosure structure accord the actual better.(2)Without considering the erection time of the bracings while using the complete analysis method for beam on elastic foundation,the calculated values of the lateral displacements and moments of the fender piles (or enclosure wall)were smaller,that was not safety in practice.(3)Research findings of this paper can provide reference for the design and construction of foundation ditch enclosure structure.